The present disclosure relates to an image processing device, an imaging device, a microscope system, an image processing method, and a computer-readable recording medium.
In recent years, techniques of recording images obtained by imaging specimens mounted on glass slides as electronic data for observation of the images by a user on a monitor has been used. As one of the techniques, a technique called as a virtual slide technique is known to sequentially stitch partial images of a specimen enlarged by a microscope to construct a high resolution image showing the whole of a specimen. The virtual slide technique is a technique acquiring a plurality of images of different fields of view in the same object, joining these images, and generating an image of an enlarged field of view in the object.
Incidentally, microscopes include a light source configured to illuminate a specimen, and an optical system configured to enlarge an image of a specimen. An image sensor configured to covert an enlarged image of a specimen to electronic data is provided subsequent to the optical system. Therefore, a problem of generation of uneven brightness in an acquired image is caused due to uneven brightness of the light source, non-uniformity in the optical system, unevenness in characteristic of the image sensor, or the like. The uneven brightness is called shading, and brightness is usually reduced with increasing distance from a center of an image that corresponds to a position of an optical axis of an optical system. Therefore, when a plurality of images is stitched to generate a virtual slide image, an unnatural boundary is disadvantageously generated at a seam between images. Furthermore, since a plurality of images is stitched to repeat shading, it looks like a specimen has periodic patterns.
Against such a problem, a shading correction technique is known to previously acquire a shading pattern as a calibration image to correct an image showing a specimen based on the calibration image. For example, in JP 2013-257422 A, a technique is disclosed to capture a reference view image being an image within a range of a predetermined field of view of a sample, move a position of the sample relative to an optical system to capture a plurality of peripheral view images each including a predetermined area within the predetermined field of view and being an image within a range of a peripheral field of view different from the range of the predetermined field of view, calculate a correction gain in each pixel of the reference view image based on the reference view image and the peripheral view image, and perform shading correction.